Previous work, performed by the applicant, and by other laboratories, has shown that the endothelial nitric oxide synthase (eNOS) is regulated post- transcriptionally via changes in mRNA half-life. The applicant has shown that during endothelial cell growth, eNOS mRNA half-life is approximately 3 times longer than when cells are quiescent. This seems to occur via interactions between novel sequences in the Enos 3'utr AND A 51 kDA protein which has been named Message of Nos DestabilizER (MONSDER). The first aim of this research will be to clone and sequence their protein, named Message of Nos DestabilizER (MONSDER). The second aim will be to over-express MONSDER in endothelial cells using a tetracycline- regulated retroviral vector system, and determine the effect of this on eNOS expression. The third aim will be to examine the relationship between eNOS mRNA stability and ribosomal assembly, and determine the effect of MONSDER over-expression on this process. Overall, these studies should provide insight into a novel mechanism of regulation of endothelial nitric oxide production. As a portion of this ward, the applicant will spend two years working in the Department of Pharmacology with Dr. T.J. Murphy, who has expertise in the area of mRNA stability. Subsequently, he will be given a faculty position and laboratory space in the Cardiology Division at Emory, and will continue to have interactions with and guidance from Drs. Murphy and Dr. David Harrison, his previous mentor and a faculty member in Cardiology. The applicant's ultimate goal is to pursue a career in basic cardiovascular research. The experience gained performing this research during the period of this award should permit Dr. Searles to become an independent investigator with the expertise and tools necessary to achieve this goal.